Textile machine

ABSTRACT

In a textile machine, in particular in a knitting machine, with  controlla working elements and an arrangement for selecting the working elements, the working elements are held in their initial position by a holding magnet and are selectively released from their initial position by an electromagnetic control system. In order to obtain a textile machine with a simple design, capable of being driven at high working speeds but in a reliable and safe manner, at least one holding magnet is rigidly fixed to the part of the textile machine that carries the working elements. A direct contact between the working elements and the moving control system is thus avoided, so that a contactless selection of the working elements is made possible.

DESCRIPTION

Textile machine, in particular a knitting machine, includingcontrollable working elements and a working element selection device,wherein the working elements are held in their initial position by aholding magnet and are selectively released from their initial positionby an electromagnetic control system.

BACKGROUND OF THE INVENTION

Textile machines of this type, in particular circular and flat bedknitting machines, are known for example from the DE 15 85 206 A2, DE 2010 973 A2, DE 21 50 360 A1, DE 25 19 896 A1 and DE 36 14 220 A2.Arrangements of this type having controllable working elements and anelectromagnetic control system are especially envisaged for the purposeof controlling patterns and as needle selection devices. Therein, theselection of a needle results from the direct effect upon the individualknitting elements, such as needles, sinkers, springs or the like, or, itis effected by controlling the ferromagnetic parts of the knittingelements indicated, whereby the electromagnetic control system movesrelative to the knitting elements located in the needle channels, in adirection which is transverse to that in which the needles aredriven-out. In order for the working elements to be got into therequisite initial position for the selection process, there are providedpermanent magnets which--by virtue of the effect of cams, if needbe--hold the working elements in their initial position for theselection process against the spring force of the take-off springs.Consequently, the permanent magnet, which is disposed in the movablecontrol system, slides over the working elements. In order to reduce thehigh degree of friction arising thereby, a rail consisting of a materialwhich is as smooth and hard as possible is placed between the poles andthe working elements in order to minimise the frictional forces and theabrasion due to the friction. The permanent magnet thereby slides along,over the working elements, until the control system, including itsselection system, arrives at the knitting element which it is intendedto select. This selection region is as wide as the working element andis separated by a narrow gap from the poles of the permanent magnet sothat the magnetic field of the permanent magnet can be neutralised inthis region by means of a control coil. Consequently, the selectedworking element is drawn out by the selection system under the influenceof the spring force of a take-off spring, while the other workingelements continue to be held in position by the magnetic poles of thepermanent magnet.

The magnetic flux in the working elements is dependent on the number ofworking elements which are respectively selected, or, which are stilladhering to the selection system so that the electromagnetic force ofattraction that is effective on the working elements also alters. Themagnetic flux of the control coil, with which the permanent magnet iscompensated in the selection region, also has to be altered in acorresponding manner. It is known from the DE 36 14 220 A2 to provide aHall probe for measuring the instantaneous magnetic flux and to alterthe current being admitted into the control coil of the electromagnet independence on the output signal of the Hall probe.

As already mentioned, in all of these conventional selection systems,there arises a considerable amount of friction between the workingelements, perhaps the sinkers, and the control system sliding thereoverand this friction has an adverse effect upon the reliability of theselection system and the whole manner of operation of the textilemachine which becomes worse, the higher the speed of operation. Sincethe friction is dependent upon the force of attraction i.e. upon thedensity of the magnet field in the working element, as well as upon thedimensions of the contacting surfaces, one had to attach greatimportance to keeping the friction small by using as small a magneticflux as possible in the conventional textile machines of this type.However, the consequence of this was that the working elements were notalways held reliably in the selection system, or, that working elements,which were not deliberately selected, became detached from the selectionsystem.

A further substantial disadvantage of conventional selection systems ofthis type consists in that there is only a short period of timeavailable during which the selection region is magnetically neutral dueto the small region in which the selection is carried out. In accordancewith a proposal known from the DE-25 56 840 A1, a plurality of selectionarrangements are arranged adjacent to one another in staggered manner inorder to thereby achieve higher working speeds of the textile machineand more positive procedures for the selection of the working elements.However, this arrangement has the disadvantage that a lot of space isrequired and, in particular, that a large number of permanent magnetsand control coils have to be used, which also substantially complicatemachines of this type as regards their manufacture, installation andservicing and give rise to a greater susceptibility to failure.

A textile machine is known from the CH-A-479 738, in which a respectiveindividual permanent magnet is provided for each needle or for eachselection sinker, each of which permanent magnets is compensated in acontrollable manner as regards its permanent-magnet-effect by means ofan appropriate excitation coil in order to bring about the selection ofthe needles. A selection device of this type is very expensive due tothe large number of individual excitation coils and the expenseassociated therewith for the respective control means and the cablingfor the excitation coils. In addition, the biassing for the sinkers bymeans of springs and the components for the release and arresting of thesinkers is very complicated and expensive. Moreover, the temperature ofthe needle bed is raised due to the excitation of the coils, which areeffectively in thermal contact therewith, which is something that isdisadvantageous.

A textile machine is known from the WO-A-9 202 672, in which anelectromagnetic control system is guided over a needle bed, whereinrespective static intermediate elements consisting of ferromagneticmaterial are provided in the needle bed for each individual needlechannel or for each needle or sinker, in an area that is basically notmagnetically excitable, in order to conduct a magnetic flux throughthese intermediate elements to the needles or to the sinkers. Themanufacture of a control system of this type or, of a needle bed of thistype is expensive due to the static intermediate elements in the needlebed.

SUMMARY OF THE INVENTION

Consequently, the object of the invention is to develop a textilemachine which does not exhibit the disadvantages of conventional textilemachines, which has a simple construction, which can be driven at highworking speeds and which nevertheless works reliably and safely.

The posed object is achieved in accordance with the invention in thatthe holding magnet is rigidly fixed to the part of the textile machinecarrying the working elements.

Due to the measure in accordance with the invention of fixing theholding magnet to the part of the textile machine carrying the workingelements, one achieves the end that a direct contact between the workingelements and the moving control system is no longer required. As aresult of this, it is possible to select the working elements in anon-contact making manner.

In accordance with an especially advantageous embodiment of theinvention, the control system is movable in non-contact making mannerover at least one external surface of the working elements. The controlsystem, which may for example be a selection system, can thus move innon-contact making manner and hence likewise, in frictionless mannerwithout exerting any mechanical effect, over the working elements.

The working elements are preferably manufactured from a ferromagneticmaterial.

In accordance with another advantageous embodiment of the invention, thecontrol system comprises at least one controllable selection magnetwhich applies a controllable magnetic flux to at least one workingelement. The controllable selection magnet of the control systemproduces either a magnetic flux or no magnetic flux or an oppositelydirected magnetic flux in the working element in accordance with the wayit is controlled so that, in dependence thereon, the working elementabutting the holding magnet in the initial position is held or releasedor is repelled.

It is especially advantageous if the working elements each comprise aspring element for biassing purposes. In each case, the spring elementsare preferably formed in one piece with the working elements.

One advantageous embodiment of the invention consists in that themagnitude of the magnetic flux of the holding magnet is selected to besuch that it holds the working elements in their initial positionagainst the spring force of the spring element. It is thereby ensuredthat, the working elements are located in the initial position at thespot where it is intended they be selected by the control system or itsselection magnet.

In this connection, it is advantageous if the selection magnetselectively produces a magnetic flux which is directed oppositely to themagnetic flux produced by the holding magnet. Thus, should a workingelement be selected, the magnetic flux of the holding magnet is reducedby the selection magnet of the control system, or it is substantiallycancelled or is even oppositely directed, so that the working elementcan be moved from the initial position or the quiescent position byvirtue perhaps, of the spring force. Due to the measure in accordancewith the invention of providing the holding magnet on the part of thetextile machine carrying the working elements, and not on the controlsystem, the force of attraction, with which the working elements abutthe intermediate elements and are placed in the initial position for theselection magnet, can be increased, without any qualms, in order toguarantee that the working elements are securely held in the initialposition. Since, in contrast to the conventional arrangement, there isno movement, and hence no friction, on the working elements inaccordance with the present invention, one can freely select the forceof attraction of the magnetic flux which is produced by the holdingmagnet in the working elements. It is especially advantageous thereby,that any increase of the magnetic force of attraction exerted by theholding magnet makes it possible to enlarge the take-off spring forcewhereby the selection process is made more positive and reliable. Inaddition, due to the high take-off force which is now possible, there isan opportunity for a direct control of the knitting implements, of theknitting needles perhaps, without any additional auxiliary elements,such as selection sinkers, so that substantially simpler componentgroups thereby result.

It is envisaged, in accordance with a preferred embodiment of theinvention, that, when selecting a working element, the selection magnetproduce a magnetic flux which substantially corresponds in strength tothe magnetic flux produced by the holding magnet but which is directedoppositely thereto. Thus, the selection of the working elements iseffected by the selection magnet in such a way that the magnetic fluxproduced in the working element by the holding magnet is substantiallycancelled or nullified by the magnetic flux produced by the selectionmagnet, or else, that it is at least reduced to an extent such that thespring force of the spring is greater than the magnetic drawing force.The working element which is to be selected can thereby be separatedfrom the holding magnet due to the effect of a take-off spring force.Should, on the other hand, a certain working element not be selected,then the selection magnet is not excited so that the magnetic fieldproduced in the working element by the holding magnet remainsundisturbed and continues to hold the working element in its initialposition.

It is advantageous if the selection magnet is an electromagnet includingan excitation coil through which a controlled current flows. Themagnetic flux of the selection magnet can be optimally controlled forthe selection process in this manner.

An embodiment, in which, as regards their surface shape and dimensions,the pole faces of the selection magnet substantially correspond to theouter surfaces of the intermediate elements which face the controlsystem, is especially advantageous. This embodiment too, makes itpossible to have a good transition of the magnetic lines of forcebetween the pole face of the selection magnet and the working elementswith a very low stray flux. Thereby, the air gap between the controlsystem, i.e. between the pole face of the selection magnet, and theouter surfaces of the working elements which face the control systemshould be as small as possible, although it has to be sufficiently largethat the parts which are moved relative to one another do not touch.

A particularly advantageous embodiment of the invention consists in thatthe control system comprises at least two control regions which arespaced from one another in the direction of movement. It is therebypossible to further optimise the control arrangement, in particular ofthe selection magnets, namely, in that as seen in the direction ofmovement, control processes, which succeed one another in space andtime, can be triggered-off without there being any relative disturbancedue to the separation in space and time.

The features in accordance with the invention can be put to particularadvantage when the textile machine is a circular or flat bed knittingmachine.

The working elements are, in advantageous manner, actuating elementswhich are effective on the implements forming the stitches, for example,the needles. Sinkers for example, can be used as the actuating elements.

The working elements are preferably placed in their starting position byat least one control element, wherein, advantageously, the controlelement is a presser cam.

In accordance with a further advantageous embodiment of the invention,the pole faces of the selection magnet are guided in non-contact makingmanner past the end faces of the actuating elements which are remotefrom the needles. Thus, the selection magnets, which are located on thecams in the case of flat bed knitting machines, are guided past thelower, narrow surface of the needle bed. Preferably, the pole faces movein a region, which corresponds to the region of the outer edges of theactuating elements, when the actuating elements are located in theinitial position.

In knitting machines, the holding magnet is preferably arranged belowthe needle bed and preferably extends in the form of a magnetic stripover the full length of the needle bed. In round knitting machines, thiscorresponds to the cylindrical periphery of the needle bed. As analternative however, it is also possible to construct the magnetic stripfrom a plurality of individual magnetic elements.

The guidance means for the magnetic field from the holding magnet to thespot at which the working elements are intended to be held in theirinitial position may be formed from appropriate parts consisting offerromagnetic material, preferably a yoke strip, wherein the pole faceof the yoke is the holding surface for a corresponding holding part ofthe working element. One has a greater degree of freedom regarding thelocation of the holding magnet due to the use of yoke elements of thistype.

In particular in connection with a flat bed knitting machine, the yokeis an L-shaped web consisting of ferromagnetic material which extendsover the full length of the holding magnet.

BRIEF SUMMARY OF THE DRAWINGS

The invention will be described hereinafter with the help of anembodiment taken with reference to the drawings. Therein:

FIG. 1 shows the arrangement in accordance with the invention based onthe example of a flat bed knitting machine, in the form of a schematiccross-sectional illustration.

FIG. 2 shows the arrangement illustrated in FIG. 1 in the form of aschematic top view.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A selection sinker 3 and a not-illustrated needle are located in each ofthe needle channels 1 of a needle bed 2 of a flat bed knitting machine.The selection sinker 3 comprises a sinker presser butt 4, a sinkercontrol butt 5, a holding part 6 and a spring part 7. A holding magnet 8is fixed to the needle bed 2, by means of bolts 9 for example, below theneedle bed 2 in a region of the needle bed 2 which is remote from theneedle bed comb. The holding magnet 8 extends, in the form of apermanent magnetic strip, over the full length of the needle bed 2 whichcomprises the needle channels 1. At the same time, an L-shaped yoke web10 is fixed by means of the bolts 9 to the holding magnet 8, once moreover the full length of the needle bed, such that the longer leg of theL-shaped yoke web 10 is located on the face of the holding magnet 8which is remote from the needle bed 2. The short leg of the L-shapedyoke web 10 extends over a part of the lower, narrow side of the needlebed 2 up to the holding part 6 of the selection sinker 3. In theembodiment illustrated in FIG. 1, the selection sinker 3 is heldmagnetically on the front surface of the short leg of the L-shaped yokeweb 10 against the spring force of the spring part 7 of the selectionsinker 3.

Furthermore, the working element selection device comprises the controlsystems 12, 13 which each include a selection magnet 14 in the form ofan electromagnet having at least one excitation coil 15. The controlsystems 12, 13 are part of a cam carriage 16, which comprises a camplate 17 including the cams 18 for the control of the sinker controlbutt 5 as well as the presser cams 19 which press the presser butt 4 ofthe selection sinker 3 downwardly against the spring force of the springpart 7 so that the holding part 6 of the selection sinker 3 touches theoppositely located front face of the short leg 11 of the L-shaped yokeweb 10, or, that it comes at least so close that the selection sinker 3is held in the initial position by the magnetic force of the holdingmagnet 8.

The cam carriage 16 moves along over the needle bed 2 whereby theselection magnet 14 is fixed to the cam carriage 16 in such a way thatits pole face is guided past, in non-contact making manner, but close tothe narrow face of the selection sinker 3 which is remote from theneedle.

In each case, the presser cams 19 are located with respect to thedirections of movement of the cam carriage 16 and hence of the controlsystems 12 and 13, as can best be seen from FIG. 2, at a predetermineddistance in front of the pole face 20 above the needle bed so that theselection sinker 3 is placed in its initial position in which it is heldby the holding magnet 8, as is apparent from FIG. 1.

Now, should a certain selection sinker 3 and hence a certain needle beselected, the selection magnet 14 is excited due to the application of acurrent to the excitation coil 15 in such a way that there appears onthe pole face 20 a magnetic flux which produces a magnetic flux in itvia the air gap between the pole face 20 and the rear end of theselection sinker 3, which magnetic flux is opposed to the magnetic fluxproduced by the holding magnet 8 and thus neutralises it, or, at leastweakens it. Due to this, the selection sinker 3 including the holdingpart 6 no longer adheres to the short leg of the L-shaped yoke web 10 sothat the selection sinker 3 is pressed upwardly due to the spring forceof its spring part 7 and its sinker control butt 5 is engaged by thecams 18, and, in known manner, it is driven-out or drawn-out for thedisplacement of the needle.

On the other hand, should a selection sinker 3 not be selected, thentoo, current is not applied to the selection magnet 14 and hence it isnot excited so that the selection sinker 3 including its holding part 6continues in this case to be held magnetically on the front face of theshort leg 11 of the L-shaped yoke web 10.

The invention has been described in terms of a preferred embodiment. Forthe skilled person, it is however possible to have innumerablevariations and modifications without thereby departing from the conceptof the invention. For example, more than two control systems could alsobe provided on a cam carriage.

I claim:
 1. A textile machine including controllable working elements arranged across a length of the textile machine and a working element selection device, each of said working elements having an external surface, wherein the working elements are held in an initial position by a holding magnet and are selectively released from the initial position by at least one electromagnetic control system, the improvement comprising the holding magnet being rigidly fixed to and extending across the length of the textile machine adjacent to the external surfaces of the working elements and the control system being movable in non-contact making manner over the length of the textile machine adjacent to the external surfaces of the working elements.
 2. A textile machine as in claim 1, wherein each working element comprises a ferromagnetic material.
 3. A textile machine as in claim 1, wherein the control system comprises at least one controllable selection magnet which applies a controllable magnetic flux to at least one working element and wherein the selection magnet selectively produces a first magnetic flux which is directed oppositely to a second magnetic flux produced by the holding magnet.
 4. A textile machine as in claim 1, wherein each working element comprises a spring part for biasing purposes.
 5. A textile machine as in claim 4, wherein the spring part is formed in one piece with the working element.
 6. A textile machine as in claim 4, wherein the magnitude of the second magnetic flux of the holding magnet is selected such that it holds the working elements in the initial position against the spring force of the spring part.
 7. A textile machine as in claim 3, wherein, when selecting a working element, the selection magnet produces the first magnetic flux so as to correspond substantially in strength to the second magnetic flux produced by the holding magnet but which is directed oppositely thereto.
 8. A textile machine as in claim 3, wherein the selection magnet is an electromagnet including at least one excitation coil through which a controlled current flows.
 9. A textile machine as in claim 3, wherein the selection magnet includes pole faces having shape and dimensions which substantially correspond to those of the external surfaces of the working elements which face the control system.
 10. A textile machine as in claim 1, wherein the control system comprises at least two control regions which are spaced apart from one another in the direction of movement.
 11. A textile machine as in claim 1, wherein the textile machine is a circular or flat bed knitting machine.
 12. A textile machine as in claim 1, wherein the working elements are needles.
 13. A textile machine as in claim 1, wherein the working elements are sinkers.
 14. A textile machine as in claim 1, wherein the working elements are placed in the initial position by at least one control element.
 15. A textile machine as in claim 14, wherein the control element is a presser cam.
 16. A textile machine as in claim 1, wherein a pole face of the selection magnet is guided in non-contact making manner past end faces of the working elements remote from the needles.
 17. A textile machine as in claim 1, wherein the holding magnet is arranged below a needle bed.
 18. A textile machine as in claim 17, wherein the holding magnet extends over the full length of the needle bed in the form of a magnetic strip.
 19. A textile machine as in claim 1, wherein a yoke strip having a yoke pole face which is a holding surface for a corresponding holding part of the working element, is connected to the holding magnet.
 20. A textile machine as in claim 19, wherein the yoke strip is an L-shaped web consisting of ferromagnetic material which extends over the full length of the holding magnet.
 21. A textile machine, comprising:a working portion having a plurality of controllable working elements arranged across a length of the working portion, each of said working elements having an external surface; a holding magnet rigidly affixed across the length of the working portion adjacent to the external surfaces of the working element for holding the working elements in an initial position; and at least one electromagnetic control system for selectively releasing the working elements from the initial position, said control system being movable in a non-contact making manner adjacent to the external surfaces of the working elements. 